Nil cannot and should not convert to a string

1 files changed, 1 insertions, 1 deletions

diff --git a/tool/merger.rb b/tool/merger.rb
index 56b7b4a068..f5ed9851c4 100755
--- a/tool/merger.rb
+++ b/tool/merger.rb
@@ -200,7 +200,7 @@ class << Merger
     else
       command = %w[git diff --color]
     end
-    IO.popen(command + [file], &:read)
+    IO.popen(command + [file].compact, &:read)
   end
 
   def commit(file)